In an inkjet printer, it is important to actuate the ink ejector with the appropriate voltage and current. However, during the operation of the printer, the effective or apparent parasitic resistance changes and this change could change the voltage and the current supplied to the ink ejector. One example of this phenomenon occurs when multiple ejectors attached to the same power line are fired or actuated simultaneously, which means that multiple ejectors are on during a particular time interval. There is a parasitic resistance associated with the power lines leading to each of the ejectors. When multiple ejectors are fired at the same time, the current passing through the power line prior to reaching the ejectors increases proportionally to the number of ejectors fired. The increasing current causes an increased voltage drop across the power line and thus reduces the voltage supplied to each ejector. Regardless of the type of ink ejectors that are used, a reduced voltage supplied to the ink ejectors may have negative effects on their operation. These negative affects may reduce print quality. For example, in inkjet printers that use heater resistors to eject ink, the heat produced by the heater resistor depends on the voltage applied to the heater resistor. Thus, when multiple ejectors attached to the same power line are actuated simultaneously, the heat produced by each ejector is reduced compared to the heat that would be produced if the ejector were actuated alone. (Actuated means “turned on”).
Other changes in the parasitic resistance of an ink jet printer may also occur due to temperature changes in the environment or changes in the circuit over time. These changes in the parasitic resistance, whether effective or actual, will also change the operational characteristics of the printer and may reduce print quality.